Seiko Silverwave diver from 1964

The introduction of the 50m Seiko SilverWave dive watch in 1961 marked a number of firsts for Seiko: it represented their first semi-serious divers watch, (although not iso-rated and therefore not qualifying as a professional divers watch by today’s standards); it was their first watch with an inner rotating timing bezel; and it was their first automatic watch with a screw-down case back. The earlier incarnations of these lovely watches were identified with the model number J12082, a numbering convention preceding the familiar eight digit system currently used by Seiko. The naming conventions for the movement calibres was similarly different, with the 20 jewel automatic 603 calibre fitted to these earlier watches essentially the same as the 6201 caliber, subsequently used with additional complications in the more celebrated 62MAS divers, world timers and numerous Seikomatic dress watches.

The main distinguishing features of the 50m version of the Silverwave, produced under the Seikomatic line, were the screw-down case back (in fact a two part affair, with a separate retaining ring screwing down over a press fit back); a conventional count-up bezel (also of two part construction); and the 20 jewel 603 movement. These watches were produced for about three years until 1964 when they were joined/replaced by a budget version marketed as the Sportsmatic Silverwave, with model number 69799, superficially identical in appearance but featuring a slightly more workmanlike 17 jewel 2451/6601 movement and, by virtue of its press-fit case back, a reduced 30m water resistance. This watch was produced at least until 1965* at which point its model number had been upgraded under the new numbering convention to 6601-7990. It is the 30m 697990 version which is the subject of this post.

My watch was secured, as is my wont, via a poorly described and photographed Ebay auction about a year ago. The description was sparse but the single photo just about good enough to allow the eagle-eyed to identify what was on offer:

Photocredit: Ebay seller

When it arrived a day or two later, I was quietly encouraged that this one would not take too much to lick into shape:

The watch was complete, in decent condition overall but a non-runner. The pistachio-ice-cream-green lume displaying tell-tale signs of encroaching mung, the bezel pip lume missing altogether and the outer crystal retaining bezel a bit on the tatty side. Removing that tatty bezel and crystal reveals the inner bezel, unconventionally a count-down bezel (10 to 60 displayed anticlockwise rather than clockwise on the count-up bezel of the 50m variant), made of black plastic, but faded to dark grey as is typical of these watches.

In fact this ghosting of the bezel is at least partly reversible though judicious cleaning with watchmakers putty but the main job with this part would be to sort the missing lume pip. These one-piece rotating bezels on the 30m variant are made entirely of plastic, with teeth to the rear engaging with a toothed wheel mounted on the crown. They can be subject to damage but the example on this watch appears fine.

The dial is not too bad at all considering it’s approaching its 50th birthday. It’s a bit dirty and the black lines marking the lume dots betraying the drooping inclination of the hour hand, causing it to come into light contact with the lume dots on its journey around the dial. Although the lume is in reasonable condition overall, I have to say its hue is more than I can tolerate and the need to relume the timing ring pip means that a hand/dial relume is on the cards. More of that later.

The movement too looks pretty good from the rear, the age of this watch (June 1964) in keeping with the Seikosha branding on the winding bridge.

We take note at this point though the broken screw head securing the movement to the movement spacer (we’ll be coming back to this in a while). Next, off comes the movement spacer (having extracted that broken screw), an operation that must precede dial removal because access to the dial feet screws is otherwise obscured. Dial off and we are into our familiar routine of breaking down the movement, winding bridge down.

Looks alright doesn’t? Rather begs the question at this point as to why it won’t run (at all). Removing the autowinding bridge exposes the train wheel and barrel bridge, and barrel ratchet wheel. If you go now and take a quick peak at a shot of a 6601A at a similar point in proceedings here, you will see that the two movements are basically the same.

We are only one step away however from discovering part of the reason this movement is stuck fast. Removal of the barrel ratchet wheel reveals considerable damage around the barrel arbor hole.

I can only imagine that a watchmaker has at some point thought to reduce barrel arbor end shake by trying to close up the hole in the bridge but it seems like a very crude approach to me. This impression is further reinforced when we turn the bridge over and we see an impression of the click spring has made its way all the way to the other side. I have no clue how that might have happened other than to suggest that the click spring came under fire when the arbor hole was receiving its punishment. Very odd.

Fortunately, the damage appears limited to the bridge, the parts beneath looking tidy and unmolested.

There is no way though that this bridge is going to find its way back onto this movement but fortunately I’ve got a whole bunch of spare 6619’s stashed away from which I can procure a replacement. A bonus in this case is an extra jewel servicing the fourth wheel where an unjeweled pivot hole does the job in the 2451/6601.

The damage to the bridge though is not sufficient on its own to prevent the movement from running (surprisingly). The principal culprit turns out to have been the remainder of that broken screw head, now lodged between the spokes of the centre wheel:

With the movement now completely dissembled, we are ready to clean the parts

before proceeding with the rebuild. I’ll gloss over most of that but pause briefly to admire the replacement train wheel and barrel bridge from the spare 6619

and the mostly complete dial side, which we neglected to cover earlier. The lack of date complications making this part of the process really straightforward.

While we are here, it is worth admiring the lovely red colour of the Diashock jewels on these earlier movements, where jewels in later period movements are more magenta in colour.

Now, before refitting the dial and hands, I dip my toe for the first time in the art of reluming and somewhat to my surprise, don’t make a complete hash of it (although still plenty of room for improvement). Here are the hands, freshly lumed and left to dry for a day

before refitting to the relumed dial

Now we can turn our attention to the case. Before:

After:

Cleaned and relumed bezel ring in

and on with the crystal (341W02AN) and then bezel (which acts as an external tension ring).

Movement back in with a fresh gasket bridging the gap between the case and a ridge on the movement ring

Now, at this point all looked good. The movement was running sweetly and timekeeping looking pretty good on the Timegrapher but with quite a lot of positional variation. Furthermore, I noticed that the balance had a marked wobble, its edge visibly moving vertically up and down during each oscillation. As I have a whole stack of 66xx series movements for spares, I secured the best looking balance from among them, gave it a thorough clean, oiled the diashock and fitted to the movement (now with auto winding bridge and weight in place).

With this balance running true, the positional variation is now very consistent and with a little extra attention to regulation, she’s running at +1 s/24h, zero beat error and 261 degrees amplitude. Excellent for such an old timer.

Two quick shots of the completed watch, fitted to a nice rubber strap

and one more, placing this beautiful little watch in its rightful place as the first in line of distinguished 1960’s 6 series Seiko dive watches.

I’ve got a Seiko Sportsmatic that has stopped working. The guy I took it to said that it was the balance that was the problem but he couldn’t find a replacement balance. He told me it was a 2451 balance and a google search led me here.
Would you be able to tell me if I can find a replacement balance anywhere?

Hi James,
The 2451 is basically an earlier incarnation of the 6601 and these are ten a’penny. You can buy a bag full of discarded movements on Ebay and with luck one or more might give up a balance in decent enough condition to serve as a substitute. Alternatively, look up the Ebay seller schillachi61 and do a search for ‘6601’. He’s got a NOS 6601 balance wheel on sale at the moment for £11.99.

Hello I have just acquired a Silver wave the same as this one. It is running ok but has a cracked case back. I’m going to give a good clean up and am wondering if you may have another case back, also a new gasket would be nice. Any other parts you may be willing to part with ? Thank you.

Unfortunately cracked case backs are not uncommon on watches from this era featuring snap on casebacks and the only options are either to live with it or to find a donor watch, compromised in other respects and which can then be found cheaply. In my case, I only have one of these watches and that is the one featured in this post, so no spares – sorry. Gaskets should be no problem to find from a watch materials house such as Jules Borel (USA) or Cousins (UK). The part number is OC3060B.

Hi Pablo, I can only think of two reasons off the top of my head. The inner edge of the crystal ought to profiled to prevent the rotating ring from lifting. If a generic crystal has been fitted in the past, it may not performing that role correctly. The second possibility is that the ring itself has distorted out of the plane and the teeth on its underside no longer mesh with the cog on the stem throughout the full 360 degrees of rotation. Good luck getting to the bottom of the problem.